This invention relates to ignition systems for multifuel engines, and more particularly, to means for varying the static timing of the same.
Ignition timing is generally defined as the time in the engine cycle at which spark plug firing occurs. It is well known in the prior art that engine efficiency and performance can be optimized by varying the engine's ignition timing. In an early patent to Norviel (U.S. Pat. No. 1,622,164) an apparatus is provided whereby the operator of an engine powered vehicle may mechanically alter the static ignition timing of the engine. A subsequent patent to Mallory (U.S. Pat. No. 1,886,566) discloses a means to vary ignition timing in combination with throttle setting.
Conventionally, engines have used only gasoline as a source of fuel. However, as gasoline becomes increasingly more scarce, and produces undesirable pollutants, alternative fuel sources are being investigated. Some automobiles are being provided with two fuel tanks. The first contains gasoline whereas the second contains an alternative fuel, such as natural gas. A manually operated lever in the dashboard allows the vehicle operator to select which fuel is burned in the engine. It has been found that engine performance and efficiency can be optimized for a particular type fuel by adjustments in various engine systems. For example, U.S. Pat. No. 3,659,574, to Reschke, discloses a means for varying engine carburetion in response to a selected one of a plurality of possible fuels. However, there is no teaching in the prior art that engine efficiency and performance may be optimized by varying static ignition timing in response to the selected one of a plurality of fuels.